Evidence-Based Reviews

Assessing decisional capacity in patients with substance use disorders

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A skilled assessment is required to determine if patients can make decisions about their care.



Ms. B, age 31, is brought to the emergency department (ED) via ambulance after emergency medical technicians used naloxone nasal spray to revive her following an overdose on heroin. She reports daily IV heroin use for the last 4 years as well as frequent use of other illicit substances, including marijuana and alprazolam, for which she does not have a prescription. She is unemployed, estranged from her family, and does not have stable housing. She refuses to be admitted to a drug rehabilitation facility for detoxification and asks to be immediately discharged.

How can you determine if Ms. B has the capacity to make decisions regarding her care?

Decisional capacity is defined as a patient’s ability to use information about an illness and the proposed treatment options to make a choice that is congruent with one’s own values and preferences.1 Determining whether a patient has adequate capacity to make decisions regarding their care is an inherent aspect of all clinician-patient interactions.

Published reports have focused on the challenges clinicians face when assessing decisional capacity in patients with psychiatric and cognitive disorders. However, there is little evidence about assessing decisional capacity in patients with substance use disorders (SUDs), even though increasing numbers of patients with SUDs are presenting to EDs2 and being admitted as inpatients in general hospitals.3 In this article, I discuss:

  • the biologic basis for impaired decision-making in patients with SUDs
  • common substance use–related conditions that may impact a patient’s decisional capacity
  • the clinical challenges and legal considerations clinicians face when assessing decisional capacity in patients with SUDs
  • how to assess decisional capacity in such patients.

Decisional capacity vs competence

“Capacity” and “competence” are not the same. Decisional capacity, which refers to the ability to make decisions, is a clinical construct that is determined by clinicians and is generally used in the acute clinical setting. Because cognition is the main determinant of capacity, conditions or treatments that affect cognition can impair an individual’s decision-making capacity.1 Decisional capacity is not a global concept but a decision-specific one, subject to fluctuations depending on the time and the nature of the decision at hand. Therefore, requests for determination of decisional capacity in the clinical setting should be specific to an individual decision or set of decisions.

In contrast, competence is an enduring legal determination of incapacitation, typically made by a probate judge. It refers to the ability of an individual to perform actions needed to put decisions into effect. Decisional capacity as assessed by a clinician often serves as the basis for petitions submitted for the purpose of competency adjudication by the judicial system.

A biologic basis for impaired decision-making?

Jeste and Saks4 suggested that addiction itself is characterized by impaired decision-making because individuals keep using a substance despite experiencing recurrent physical, psychologic, or social problems caused or worsened by the substance. Several studies suggest there may be a biologic basis for impaired decision-making in these patients, even in the absence of severe psychiatric or cognitive disorders.

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